The Fluid Properties node adds the momentum and continuity equations solved by the physics interface, except for volume forces which are added by the
Volume Force feature. The node also provides an interface for defining the material properties of the fluid.
The default Absolute pressure pA is
p+pref, where
p is the dependent pressure variable from the Navier-Stokes or RANS equations, and
pref is from the user input defined at the physics interface level. When
pref is nonzero, the physics interface solves for a gauge pressure. If the pressure field instead is an absolute pressure field,
pref should be set to 0.
The Absolute pressure field can be edited by clicking
Make All Model Inputs Editable (
) and entering the desired value in the input field.
The Dynamic viscosity μ describes the relationship between the shear rate and the shear stresses in a fluid. Intuitively, water and air have low viscosities, and substances often described as thick (such as oil) have higher viscosities.
Using the built-in variable for the shear rate magnitude, spf.sr, makes it possible to define arbitrary expressions of the dynamic viscosity as a function of the shear rate.